Flutter中使用image_picker拍照并上传

1. 安装插件

配置 image_picker 插件。

dependencies:
  flutter:
    sdk: flutter
  flutter_localizations:
    sdk: flutter
  date_format: ^1.0.6
  flutter_cupertino_date_picker: ^1.0.26+2 
  flutter_swiper: ^1.1.6
  fluttertoast: ^7.1.6
  http: ^0.12.2
  flutter_html: ^1.1.0
  flutter_inappwebview: ^4.0.0+4
  device_info: ^1.0.0
  amap_location: ^0.2.0
   
  # 上传图片
  dio: ^3.0.10

  # 拍照上传
  image_picker: ^0.6.7+21

在pubspec.yaml中配置保存后，在VS Code环境中会自动下载依赖包。

如果无法正常下载，执行 flutter pub get 。

2. 引入依赖

在需要用到的该插件的文件中引入插件包。

import 'package:image_picker/image_picker.dart';

3. 使用插件

// 图片文件
File _image;
// 实例化
final picker = ImagePicker();

// 获取图片方法
Future getImage() async {
    final pickedFile = await picker.getImage(
        // 拍照获取图片
        // source: ImageSource.camera,

        // 手机选择图库
        source: ImageSource.gallery,
        // 图片的最大宽度
        maxWidth: 400

    );
    // 更新状态
    setState(() {
        if (pickedFile != null) {
            _image = File(pickedFile.path);
        } else {
            print('没有选择任何图片');
        }
    });
}

4. 结合Dio实现上传图片

引入插件包。

import 'package:dio/dio.dart';

编写上传的方法。

var dio = Dio();

// 上传图片的方法
void uploadImg(imageUrl) async{
    FormData formData = FormData.fromMap({
        "name": "admin",
        "password": 123456,
        "file": await MultipartFile.fromFile(
            imageUrl,
            filename: "avatar.img"
        )
    });
    var result = await dio.post("http://js.itying.com/imgupload", data: formData);
    print(result);
}

5. 完整示例

import 'dart:io';
import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';

class ImagePickerPage extends StatefulWidget {
    @override
    State<StatefulWidget> createState() {
        return _ImagePickerState();
    }
}

class _ImagePickerState extends State<ImagePickerPage> {
    
    // 图片文件
    File _image;
    // 实例化
    final picker = ImagePicker();
    // 获取图片
    Future getImage() async {
        final pickedFile = await picker.getImage(
            // 拍照获取图片
            // source: ImageSource.camera,

            // 手机选择图库
            source: ImageSource.gallery,
            // 图片的最大宽度
            maxWidth: 400

        );
        // 更新状态
        setState(() {
            if (pickedFile != null) {
                _image = File(pickedFile.path);
                // 上传图片到服务器
                uploadImg(pickedFile.path);
            } else {
                print('没有选择任何图片');
            }
        });
    }


    var dio = Dio();
    // 上传图片的方法
    void uploadImg(imageUrl) async{
        FormData formData = FormData.fromMap({
            "name": "admin",
            "password": 123456,
            "file": await MultipartFile.fromFile(
                imageUrl,
                filename: "avatar.img"
            )
        });
        var result = await dio.post("http://js.itying.com/imgupload", data: formData);
        print(result);
    }

    @override
    Widget build(BuildContext context) {
        return Scaffold(
            appBar: AppBar(
                title: Text("ImagePicker"),
            ),
            body: SingleChildScrollView(
                child: Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                        // 点击按钮
                        RaisedButton(
                            onPressed: getImage,
                            child: Text("获取图片"),
                        ),
                        // 展示图片
                        Center(
                            child: _image == null
                            ? Text('没有选择任何图片')
                            : Image.file(_image),
                        ),
                    ],
                )
            )
        );
    }
}

参考：

https://pub.flutter-io.cn/packages/dio

https://pub.flutter-io.cn/packages/image_picker